A unipolar quantum dot diode structure for advanced quantum light sources

TL;DR

This paper presents a novel n+-i-n++ diode structure embedding quantum dots that enables spectral tuning, deterministic charge control, and high-quality single-photon emission with minimal spectral diffusion, advancing quantum light source technology.

Contribution

The study introduces a new unipolar diode design for quantum dots that achieves spectral tuning and stable, indistinguishable single-photon emission with high two-photon interference visibility.

Findings

Achieved blinking-free, high-indistinguishability single-photon emission.

Observed no spectral diffusion or decoherence above 9 ns timescales.

Photon linewidth deviates from Fourier limit by only 1.68.

Abstract

Triggered, indistinguishable, single photons play a central role in various quantum photonic implementations. Here, we realize a novel n$^+-$i$-$n$^{++}$ diode structure embedding semiconductor quantum dots: the gated device enables spectral tuning of the transitions and deterministic control of the observed charged states. Blinking-free single-photon emission and high two-photon indistinguishability is observed. The linewidth's temporal evolution is investigated for timescales spanning more than $6$ orders of magnitude, combining photon-correlation Fourier spectroscopy, high-resolution photoluminescence spectroscopy, and two-photon interference (visibility of $V_{\text{TPI, 2ns}}=\left(85.5\pm2.2\right){\%}$ and $V_{\text{TPI, 9ns}}=\left(78.3\pm3.0\right){\%}$). No spectral diffusion or decoherence on timescales above $\sim 9\,\text{ns}$ is observed for most of the dots, and the emitted photons' linewidth $\left(\left(420\pm30\right)\text{MHz}\right)$ deviates from the Fourier-transform limit only by a factor of $1.68$. Thus, for remote TPI experiments, visibilities above $74\%$ are anticipated. The presence of n-doping only signifies higher available carrier mobility, making the presented device highly attractive for future development of high-speed tunable, high-performance quantum light sources.